Note: Descriptions are shown in the official language in which they were submitted.
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HARDMETAL COMPOSITIONS WITH NOVEL BINDER COMPOSITIONS
Background
[0002] This application relates to hardmetal compositions,
their fabrication techniques, and associated applications.
[0003] Hardmetals include various composite materials and are
specially designed to be hard and refractory, and exhibit
strong resistance to wear. Examples of widely-used hardmetals
include sintered or cemented carbides or carbonitrides, or a
1o combination of such materials. Some hardmetals, called
cermets, have compositions that may include processed ceramic
particles (e.g., TiC) bonded with binder metal particles.
Certain compositions of hardmetals have been documented in the
technical literature. For example, a comprehensive
compilation of hardmetal compositions is published in Brookes'
World Dictionary and Handbook of Hardmetals, sixth edition,
International Carbide Data, United Kingdom (1996).
[0004] Hardmetals may be used in a variety of applications.
Exemplary applications include cutting tools for cutting
metals, stones, and other hard materials, wire-drawing dies,
knives, mining tools for cutting coals and various ores and
rocks, and drilling tools for oil and other drilling
applications. In addition, such hardmetals also may be used
to construct housing and exterior surfaces or layers for
various devices to meet specific needs of the operations of
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ATTORNEY DOCKET N(P14 7'1-002WO1
the devices or the environmental conditions under which the
devices operate.
[0005] Many hardmetals may be formed by first dispersing hard,
refractory particles of carbides or carbonitrides in a binder
matrix and then pressing and sintering the mixture. The
sintering process allows the binder matrix to bind the
particles and to condense the mixture to form the resulting
hardmetals. The hard particles primarily contribute to the
1o hard and refractory properties of the resulting hardmetals.
Summary
[0006] The hardmetal materials described below include
materials comprising hard particles having a first material,
and a binder matrix having a second, different material. The
hard particles are spatially dispersed in the binder matrix in
a substantially uniform manner. The first material for the
hard particles may include, for example, materials based on
tungsten carbide, materials based on titanium carbide, and
materials based on a mixture of tungsten carbide and titanium
carbide. The second material for the binder matrix may
include, among others, rhenium, a mixture of rhenium and
cobalt, a nickel-based supperalloy, a mixture of a nickel
based supperalloy and rhenium, a mixture of a nickel-based
supperalloy, rhenium and cobalt, and these materials mixed
with other materials. The nickel-based supperalloy may be in
the y-y' metallurgic phase.
[0007] In various implementations, for example, the volume of
the second material may be from about 3% to about 40% of a
total volume of the material. For some applications, the
binder matrix may comprise rhenium in an amount greater than
25% of a total weight of the material. In other applications,
the second material may include a Ni-based supperalloy. The
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Ni-based superalloy may include Ni and other elements such
as Re for certain applications.
[0008] Fabrication of the hardmetal materials of this
application may be carried out by, according to one
implementation, sintering the material mixture under a
vacuum condition and performing a solid-phase sintering
under a pressure applied through a gas medium.
[0009] Advantages arising from these hardmetal materials
and composition methods may include one or more of the
following: superior hardness in general, enhanced hardness
at high temperatures, and improved resistance to corrosion
and oxidation.
00010] These and other features, implementations, and
advantages are now described in detail with respect to the
drawings, the detailed description, and the claims.
According to one aspect of the present invention,
there is provided a material, comprising: hard particles
comprising a first material which comprises a nitride; and a
binder matrix comprising a second, different material, a
volume of said second material being from about 3% to about
40% of a total volume of the material, said binder matrix
comprising rhenium or nickel-based superalloy, wherein said
hard particles are spatially dispersed in said binder matrix
in a substantially uniform manner.
According to another aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
comprising a second, different material, a volume of said
second material being from about 3% to about 40% of a total
volume of the material, said binder matrix comprising
rhenium and a Ni-based superalloy, wherein said hard
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particles are spatially dispersed in said binder matrix in a
substantially uniform manner.
According to still another aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material which comprises, Mo2C
and TiC; and a binder matrix comprising a second, different
material, a volume of said binder matrix being from about
3% to about 40% of a total volume of the material, said
binder matrix comprising rhenium, wherein said hard
particles are spatially dispersed in said binder matrix in a
substantially uniform manner.
According to yet another aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
comprising a second, different material which comprises a
nickel-based superalloy and at least one of a second,
different nickel-based superalloy; rhenium and cobalt;
cobalt; nickel; iron; molybdenum; and chromium, wherein said
hard particles are spatially dispersed in said binder matrix
in a substantially uniform manner.
According to a further aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material which comprises TiC
and TiN; and a binder matrix comprising a second, different
material which comprises a Re or a Ni-based superalloy and
at least one of Ni, Mo, and M02C, wherein said hard particles
are spatially dispersed in said binder matrix in a
substantially uniform manner.
According to yet a further aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
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comprising a second, different material which comprises a
nickel-based superalloy, wherein said hard particles are
spatially dispersed in said binder matrix in a substantially
uniform manner wherein said Ni-based superalloy is in a y-
y' phase.
According to still a further aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
comprising a second, different material which comprises a
nickel-based superalloy which comprises nickel and other
elements, said other elements comprising Co, Cr, Al, Ti, Mo,
Nb, W, Zr, and Re, wherein said hard particles are spatially
dispersed in said binder matrix in a substantially uniform
manner.
According to another aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
comprising a second, different material, a volume of said
second material being from about 3% to about 40% of a total
volume of the material, said binder matrix comprising
rhenium and at least one of nickel (Ni); molybdenum (Mo);
iron (Fe); and chromium (Cr), wherein said hard particles
are spatially dispersed in said binder matrix in a
substantially uniform manner, wherein said first material
comprises at least one of a boride, a silicide, a carbide,
and a nitride.
According to yet another aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
comprising a second, different material, which comprises a
nickel-based superalloy, wherein said hard particles are
spatially dispersed in said binder matrix in a substantially
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uniform manner wherein said Ni-based superalloy comprises
Re, wherein said first material comprises at least one of a
nitride, a carbide, a boride, and a silicide.
According to another aspect of the present
invention, there is provided a material, comprising: hard
particles comprising a first material; and a binder matrix
comprising a second, different material, which comprises a
nickel-based superalloy, wherein said hard particles are
spatially dispersed in said binder matrix in a substantially
uniform manner, wherein said Ni-based superalloy comprises
Re, wherein said second material further comprises at least
one of Ni, Fe, Mo and Cr.
According to still another aspect of the present
invention, there is provided a method, comprising: forming a
grade powder by mixing a powder of hard particles with a
binder matrix material comprising rhenium; and processing
the grade powder to use the binder matrix material to bind
the hard particles to produce a solid hardmetal material,
wherein the processing comprises (1) sintering the grade
powder in a solid phase under a vacuum condition at a
temperature below an eutectic temperature of the hard
particles and the binder matrix material to remove or
eliminate interconnected porosity and to solidify the grade
powder, and (2) subsequently sintering the solidified grade
powder in a solid phase under a pressure in an inert gas
medium and below the eutectic temperature to produce a
densified material without further performing a rapid
omnidirectional compaction (ROC) process.
According to yet another aspect of the present
invention, there is provieed a method, comprising: forming a
grade powder by mixing a powder of hard particles with a
binder matrix material comprising a nickel-based superalloy;
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sintering the grade powder in a solid state phase under a
vacuum condition at a temperature below an eutectic
temperature of the hard particles and the binder matrix
material to remove or eliminate interconnected porosity to
produce a solid hardmetal material from the grade powder,
wherein the binder matrix material binds the hard particles
in the solid hardmetal material; and subsequently sintering
the solid hardmetal material in a solid phase under a
pressure in an inert gas medium and below the eutectic
temperature to produce a densified material without further
performing a rapid omnidirectional compaction (ROC) process.
Drawing Description
[0011] FIG. 1 shows one exemplary fabrication flow in
making a hardmetal according to one implementation.
[0012] FIG. 2 shows an exemplary two-step sintering
process for processing hardmetals in a solid state.
[0013] FIGS. 3, 4, 5, 6, 7, and 8 show various measured
properties of selected exemplary hardmetals.
Detailed Description
[0014] Compositions of hardmetals are important in that
they directly affect the technical performance of the
hardmetals in their intended applications, and processing
conditions and equipment used during fabrication of such
hardmetals. The hardmetal compositions also can directly
affect the cost of the raw materials for the harmetals, and
the costs associated with the fabrication processes. For
these and other reasons, extensive efforts have been made in
the hardmetal industry to develop technically superior and
economically feasible
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compositions for hardmetals. This application describes,.
among other features, material compositions for hardmetals
with selected binder matrix materials that, together, provide
performance advantages.
[0015] Material compositions for hardmetals of interest
include various hard particles and various binder matrix
materials. In general, the hard particles may be formed from
carbides of the metals in columns IVB (e.g., TiC, ZrC,'HfC),'
VB (e.g., VC, NbC, TaC), and VIB (e.g., Cr3C2, Mo2C, WC) in the
Periodic Table of Elements. In addition, nitrides formed by
metals elements in columns IVB (e.g., TiN, ZrN, HfN) and VB
(e.g., VN, NbN, and TaN) in the Periodic Table of Elements may
also be used. For example, one material composition for hard
particles that is widely used for many hardmetals'is a
tungsten carbide, e.g., the mono tungsten carbide (WC).
Various nitrides may be mixed with carbides to form the hard
particles. Two or more of the above and other carbides and
nitrides may be combined to form WC-based hardmetals or WC-
free hardmetals. Examples of mixtures of different carbides
include but are not limited to a mixture of WC and TiC, and a
mixture of WC, TiC, and TaC.
[0016] The material composition of the binder matrix, in
addition to providing a matrix for bonding the hard particles
together, can significantly affect the hard and refractory
properties of the resulting hardmetals. In general, the
binder matrix may include one or more transition metals in the
eighth column of the Periodic Table of Elements, such as
cobalt (Co), nickel (Ni), and iron (Fe), and the metals in the
6B column such as molybdenum (Mo) and chromium (Cr). Two or
more of such and other binder metals may be mixed together to
form desired binder matrices for bonding suitable hard,
particles. Some binder matrices, for example, use
combinations of Co, Ni, and Mo with different relative
weights.
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[0017] The hardmetal compositions described here were in part
developed based on a recognition that the material composition
of the binder matrix may be specially configured and tailored
to provide high-performance hardmetals to meet specific needs
of various applications. In particular, the material
composition of the binder matrix has significant effects on
other material properties of the resulting hardmetals, such as
the elasticity, the rigidity, and the strength parameters
(including the transverse rupture strength, the tensile
strength, and the impact strength). Hence, the inventor
recognized that it was desirable to provide the proper
material composition for the binder matrix to better match the
material composition of the hard particles and other
components of the hardmetals in order to enhance the material
properties and the performance of the resulting hardmetals.
[0018] More specifically, these hardmetal compositions use
binder matrices that include rhenium, a nickel-based
supperalloy or a combination of at least one nickel-based
supperalloy and other binder materials. Other suitable binder
materials may include, among others, rhenium (Re) or cobalt.
A Ni-based superalloy exhibits a high material strength at a
relatively high temperature. The resulting hardmetal formed
with such a binder material can benefit from the high material,
strength at high temperatures of rhenium and Ni-supperalloy
and exhibit enhanced performance at high temperatures. In
addition, a Ni-based supperalloy also exhibits superior
resistance to corrosion and oxidation, and thus, when used as
a binder material, can improve the corresponding resistance of
the hardmetals.
[0019] The compositions of the hardmetals described in this
application may include the binder matrix material from about
3% to about 40% by volume of the total materials in the
hardmetals so that the corresponding volume percentage of the
hard particles is about from 97% to about 60%, respectively.
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Within the above volume percentage range, the binder matrix
material in certain implementations may be from about 4% to
about 35% by volume out of the volume of the total hardmetal
materials. More preferably, some compositions of the
hardmetals may have from about 5% to about 30% of the binder
matrix material by volume out of the volume of the total
hardmetal materials. The weight percentage of the binder
matrix material in the total weight of the resulting
hardmetals may be derived from the specific compositions of
1o the hardmetals.
[0020] In various implementations, the binder matrices may be
formed primarily by a nickel-based supperalloy, and by various
combinations of the nickel-based superalloy with other
elements such as Re, Co, Ni, Fe, Mo, and Cr. A Ni-based
supperalloy of interest may comprise, in addition to Ni,
elements Co, Cr, Al, Ti, Mo, W, and other elements such as Ta,
Nb, B, Zr and C. For example, Ni-based superalloys may
include the following constituent metals in weight percentage
of the total weight of the supperalloy: Ni from about 30% to
about 70%, Cr from about 10% to about 30%, Co from about 0% to
about 25%, a total of Al and Ti from about 4% to about 12%, Mo
from about 0% to about 10%, W from about 0% to about 10%, Ta
from about 0% to about 10%, Nb from about 0% to about 5%, and
Hf from about 0% to about 5%. Ni-based superalloys may also
include either or both of Re and Hf, e.g., Re from 0% to about
10%, and Hf from 0% to about 5%. Ni-based supperalloy with Re
may be used in applications under high temperatures. A Ni-
based supper alloy may further include other elements, such as
B, Zr, and C, in small amounts.
[0021] TaC and NbC have similar properties to a certain extent
and may be used to partially or completely substitute or
replace each other in hardmetal compositions in some
implementations. Either one or both of HfC and NbC also may
be used to substitute or replace a part or all of TaC in
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hardmetal designs. WC, TiC, TaC may be produced individually
or in mixture together in a form of solid solution. When a
mixture is used, the mixture may be selected from at least one
from a group consisting of (1) a mixture of WC, TiC, and TaC,
(2) a mixture of WC, TiC, and NbC, (3) a mixture of WC, TiC,
and at least one of TaC and NbC, and (4) a mixture of WC, TiC,
and at least one of HfC and NbC. A solid solution of multiple
carbides may exhibit better properties and performances than a
mixture of several carbides. Hence, hard particles may be
selected from at least one from a group consisting of (1) a
solid solution of WC, TiC, and TaC, (2) a solid solution of
WC, TiC, and NbC, (3) a solid solution of WC, TiC, and at
least one of TaC and NbC, and (4) a solid solution of WC, TiC,
and at least one of HfC and NbC.
[0022] The nickel-based superalloy as a binder material may be
in a y-y' phase where the y' phase with a FCC structure mixes
with the y phase. The strength increases with temperature
within a certain extent. Another desirable property of such a
Ni-based supperalloy is its high resistance to oxidation and
corrosion.. The nickel-based superalloy may be used to either
partially or entirely replace Co in various Co-based binder
compositions. As demonstrated by examples disclosed in this
application, the inclusion of both of rhenium and a nickel-
based superalloy in a binder matrix of a hardmetal can
significantly improve the performance of the resulting
hardmetal by benefiting from the superior performance at high
temperatures from presence of Re while utilizing the
relatively low-sintering temperature of the Ni-based
supperalloy to maintain a reasonably low sintering temperature
for ease of fabrication. In addition, the relatively low
content of Re in such binder compositions allows for reduced
cost of the binder materials so that such materials be
economically feasible.
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[0023] Such a nickel-based superalloy may have a percentage
weight from several percent to 100% with respect to the total
weight of all material components in the binder matrix based
on the specific composition of the binder matrix. A typical
nickel-based superalloy may primarily comprise nickel and
other metal components in a y-y' phase strengthened state so
that it exhibits an enhanced strength which increases as
temperature rises.
[0024] Various nickel-based superalloys may have a melting
to point lower than the common binder material cobalt, such as
alloys under the trade names Rene-95, Udimet-700, Udimet-720
from Special Metals which comprise primarily Ni in combination
with Co, Cr, Al, Ti, Mo, Nb, W, B, and Zr. Hence, using such
a nickel-based supperalloy alone as a binder material may not
increase the melting point of the resulting hardmetals in
comparison with hardmetals using binders with Co.
[0025] However, in one implementation, the nickel-based
supperalloy can be used in the binder to provide a high
material strength and to improve the material hardness of the
resulting hardmetals, at high temperatures near or above 500
C. Tests of some fabricated samples have demonstrated that
the material hardness and strength for hardmetals with a Ni-
based superalloy in the binder can improve significantly,
e.g., by at least 10%, at low operating temperatures in
comparison with similar material compositions without Ni-based
superalloy in the binder. The following table show measured
hardness parameters of samples P65 and P46A with Ni-based
supperalloy in the binder in comparison with samples P49 and
P47A with pure Co as the binder, where the compositions of the
samples are listed in Table 4.
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Effects of Ni-based Superalloy (NS) in Binder
Sample Co or NS Binder Hv at Room Ksc at room Comparison
Code Temperature temperature
Name (Kg/mm2) (x106 Pa-m112)
P49 Co: 10 volume% 2186 6.5
P65 NS: 10 volume% 2532 6.7 Hv is about 16%
greater than
that of P49
P47A Co: 15 volume% 2160 6.4
P46A NS: 15 volume% 2364 6.4 Hv is about 10%
greater than
that of P47A
[0026] Notably, at high operating temperatures above 500 C,
hardmetal samples with Ni-based supperalloy in the binder can.
exhibit a material hardness that is significantly higher than
that of similar.iardmetal samples without having a Ni-based
supperalloy in the binder. In addition, Ni-based supperalloy
as a binder material can also improve the resistance to
corrosion of the resulting hardmetals or cermets in comparison
to with hardmetals, or cermets using the conventional cobalt as
the binder.
[0027] A nickel-based superalloy may be used alone or in
combination with other elements to form a desired binder
matrix. Other elements that may be combined with the nickel-
based superalloy to form a binder matrix include but are not
limited to, another nickel-based supperalloy, other non-
nickel-based alloys, Re, Co, Ni, Fe, Mo, and Cr.
[0028] Rhenium as a binder material may be used to provide
strong bonding of hard particles and in particular can produce
a high melting point for the resulting hardmetal material.
The.melting point of rhenium is about 3180 C, much higher than
the melting point of 1495 C of the commonly-used cobalt as a
binder material. This feature of rhenium partially
contributes to the enhanced performance of hardmetals with
binders using Re, e.g., the enhanced hardness and strength of
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the resulting hardmetals at high temperatures. Re also has
other desired properties as a binder material. For example,
the hardness, the transverse rapture strength, the fracture
toughness, and the melting point of the hardmetals with Re in
their binder matrices can be increased significantly in
comparison with similar hardmetals without Re in the binder
matrices. A hardness Hv over 2600 Kg/mm2 has been achieved in
exemplary WC-based hardmetals with Re in the binder matrices.
The melting point of some exemplary WC-based hardmetals, i.e.,
the sintering temperature, has shown to be greater than 2200
C. In comparison, the sintering temperature for WC-based
hardmetals with Co in the binders in Table 2.1 in the cited
Brookes is below 1500 C, A hardmetal with a high sintering
temperature allows the material to operate at a high
temperature below the sintering temperature. For example,
tools based on such Re-containing hardmetal materials may
operate at high speeds to reduce the processing time and the
overall throughput of the processing.
[0029] The use of Re as a binder material in hardmetals,'
however, may present limitations in practice. For example,
the desirable high-temperature property of Re generally leads
to a high sintering temperature for fabrication. Thus, the
oven or furnace for the conventional sintering process needs
to operate at or above the high sintering temperature. Ovens
or furnaces capable of operating at such high temperatures,
e.g., above 2200 C, can be expensive and may not be widely
available for commercial use. U. S. Patent No. 5,476,531
discloses a use of a rapid omnidirectional compaction (ROC)
method to reduce the processing temperature in manufacturing
WC-based hardmetals with pure Re as the binder material from
6% to 18% of the total weight of each hardmetal. This ROC
process, however, is still expensive and is generally not
suitable for commercial fabrication.
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[0030] One potential. advantage of the hardmetal compositions
and the composition methods described here is that they may
.provide or allow for a more practical fabrication process for
fabricating hardmetals with either Re or mixtures of Re with
other binder materials in the binder matrices. In particular,
this two-step process makes it possible to fabricate
hardmetals where Re is more than 25% of the total weight of
the resulting hardmetal. Such hardmetals with more than 25%
Re may be used to achieve high hardness and material strength
to at high temperatures.
[0031] Another limitation of using pure Re as a binder
material for hardmetals is that Re oxidizes severely in air at
or above about 350 C. This poor oxidation resistance may
dramatically reduce the use of pure Re as binder for any
application. above about 300 C. Since Ni-based superalloy has
exceptionally strength and oxidation resistance under 1000 C,
a mixture of a Ni-based superalloy and Re where Re is the
dominant material in the binder may be used to improve the
strength and oxidation resistance of the resulting hardmetal
using such a mixture as the binder. On the other hand, the
addition of Re into a binder primarily comprised of a Ni-based
superalloy can increase the melting range of the resulting
hardmetal, and improve the high temperature strength and creep
resistance of the Ni-based superalloy binder.
[0032] In general, the percentage weight of the rhenium in the
binder matrix should be between a several percent to
essentially 100% of the total weight of the binder matrix in a
hardmetal. Preferably, the percentage weight of rhenium in
the binder matrix should be at or above 5%. In particular,
the percentage weight of rhenium in the binder matrix may be
at or above 10% of the binder matrix. In some
implementations, the percentage weight of rhenium in the
binder matrix may be at or above 25% of the total weight of
the resulting hardmetal. Hardmetals with such high
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concentration of Re may be fabricated at relatively low
temperatures with-a two-step process described in this
application.
[0033] Since rhenium is generally more expensive than other
materials used in hardmetals, cost should be considered in
designing binder matrices that include rhenium. Some of the
examples given below reflect this consideration. In general,
according to one implementation, a hardmetal composition
includes dispersed hard particles having a first material, and
1o a binder matrix having a second, different material that
includes rhenium, where the hard particles are spatially.
dispersed in the binder matrix in a substantially uniform
manner. The binder matrix may be a mixture of Re and other
binder materials to reduce the total content of Re to in part
reduce the overall cost of the raw materials and in part to
explore the presence of other binder materials to enhance the
performance of the binder matrix. Examples of binder matrices
having mixtures of Re and other binder materials include,
mixtures of Re and at least one Ni-based supperalloy, mixtures
of Re, Co and at least one Ni-based supperalloy, mixtures. of
Re and Co, and others.
[0034] TABLE 1 lists some examples of hardmetal compositions
of interest. In this table, WC-based compositions are
referred to as "hardmetals" and the TiC-based compositions are
referred to as "cermets." Traditionally, TiC particles bound
by a mixture of Ni and Mo or a mixture of Ni and Mo2C are
cermets. Cermets as described here further include hard
particles formed by mixtures of TiC and TiN, of TiC, TiN, WC,
TaC, and NbC with the binder matrices formed by the.mixture of
Ni and Mo or the mixture of Ni and M02C. For each hardmetal
composition, three different weight percentage ranges for the
given binder material in the are listed. As an example, the
binder may be a mixture of a Ni-based supperalloy and cobalt,
and the hard particles may a mixture of WC, TiC, TaC, and NbC.
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In this composition, the binder may be from about 2% to about
40% of the total weight of the hardmetal. This range may be
set to from about 3% to about 35% in some applications and may
be further limited to a smaller range from about 4% to about
30% in other applications.
TABLE 1
(NS: Ni-based supperalloy)
Composition
Binder 1=t Binder 2 d Binder 3=d Binder
for
Composition Wt.% Range Wt.% Range Wt.% Range
Hard Particles
WC 4 to 40 5 to 35. 6 to 30
Re
WC-TiC-TaC-NbC 4 to 40 5 to 35 6 to 30
WC 2 to 30 3 to 25 4 to 20
NS
WC-TiC-TaC-NbC 2 to 30 3 to 25 4 to 20
WC 2 to 40 3 to 35 4 to 30
Hardmetals NS-Re
WC-TiC-TaC-NbC 2 to 40 3 to 35 4 to 30
WC 2 to 40 3 to 35 4 to 30
Re-Co
WC-TiC-TaC-NbC 2 to 40 3 to 35 4 to 30
WC 2 to 40 3 to 35 4 to 30
NS-Re-Co
WC-TiC-TaC-NbC 2 to 40 3 to 35 4 to 30
Mo2C-TiC 5 to 40 6 to 35 8 to 40
NS Mo2C-TiC-TiN-
5 to 40 6 to 35 8 to 40
WC-TaC-NbC
Mo2C-TiC 10 to.55 12 to 50 15 to 45
Cermets Re Mo2C-TiC-TiN-
to 55 12 to 50 15 to 45
WC-TaC-NbC
Mo2C-TiC 5 to 55 6 to 50 8 to 45
NS-Re Mo2C-TiC-TiN-
5 to 55 6 to 50 8 to 45
WC-TaC-NbC
10 [0035] Fabrication of hardmetals with Re or a nickel-based
supperalloy in binder matrices may be carried out as follows.
First, a powder with desired hard particles such as one or
more carbides or carbonitrides is prepared. This powder may
include a mixture of different carbides or a mixture of
carbides and nitrides. The powder is mixed with a suitable
binder matrix material that includes Re or a nickel-based
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supperalloy. In addition, a pressing lubricant, e.g., a wax,
may be added to the mixture.
[0036] The mixture of the 'hard particles, the binder matrix
material, and the lubricant is mixed through a milling or
attriting process by milling or attriting over a desired
period, e.g., hours, to fully mix the materials so that each
hard particle is coated with the binder matrix material to
facilitate the binding of the hard particles in the subsequent
processes. The hard particles should also be coated with the
l0 lubricant material to lubricate the materials to facilitate
the mixing process and to reduce or eliminate oxidation of the
hard particles. Next, pressing, pre-sintering, shaping, and
final sintering are subsequently performed to the milled
mixture to form the resulting hardmetal. The sintering
process is a process for converting a powder material into a
continuous mass by heating to a temperature that is below the
melting temperature of the hard particles and may be performed
after preliminary compacting by pressure. During this
process, the binder material is densified to form a continuous
binder matrix to bind hard particles therein. One or more
additional coatings may be further formed on a surface of the
resulting hardmetal to enhance the performance of the
hardmetal. FIG. 1 is a flowchart for this implementation of
the fabrication process.
[0037] In one implementation, the manufacture process for
cemented carbides includes wet milling in solvent, vacuum
drying, pressing, and liquid-phase sintering in vacuum. The
temperature of the liquid-phase sintering is between melting
point of the binder material (e.g., Co at 1495 C) and the
eutectic temperature of the mixture of hardmetal (e.g., WC-Co
at 1320 C). In general, the sintering temperature of cemented
carbide is in a range of 1360 to 1480 C. For new materials
with low concentration of Re or a Ni-based supperalloy in
binder alloy, manufacture process is same as conventional
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cemented carbide process. The principle of liquid phase
sintering in vacuum is applied in here. The sintering
temperature is slightly higher than the eutectic temperature
of binder alloy and carbide. For example, the sintering
condition of P17 ( 25% of Re in binder alloy, by weight ) is
at 1700 C for one hour in vacuum.
[0038] FIG. 2 shows a two-step fabrication process based on a
solid-state phase sintering for fabricating various hardmetals
described in this application. Examples of hardmetals that
to can be fabricated with this two-step sintering method include
hardmetals with a high concentration of Re in the binder
matrix that would otherwise require the liquid-phase sintering
at high temperatures. This two-step process may be
implemented at relatively low temperatures, e.g., under 2200
C, to utilize commercially feasible ovens and to produce the
hardmetals at reasonably low costs. The liquid phase
sintering is eliminated in this two-step process because the
liquid phase sintering may not be practical due to the
generally high eutectic temperatures of the binder alloy and
carbide. As discussed above, sintering at such high
temperatures requires ovens operating at high temperatures
which may not be commercially feasible.
[0039] The first step of this two-step process is a vacuum
sintering where the mixture materials for the binder matrix
and the hard particles are sintered in vacuum. The mixture is
initially processed by, e.g., wet milling, drying, and
pressing, as performed in conventional processes for
fabricating cemented carbides. This first step of sintering
is performed at a temperature below the eutectic temperature
of the binder alloy and the hard particle, materials to remove
or eliminate the interconnected porosity. The second step is
a solid phase sintering at a temperature below the eutectic
temperature and under a pressured condition to remove and
eliminate the remaining porosities and voids left in the
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sintered mixture after the first step. A hot isostatic
pressing (HIP) process may be used as this second step
sintering. Both heat and pressure are applied to the material
during the sintering to reduce the processing temperature
which would otherwise be higher in absence of the pressure. A
gas medium such as an inert gas may be used to apply and
transmit the pressure to the sintered mixture. The pressure
may be at or over 1000 bar. Application of pressure in the
HIP process lowers the required processing temperature and
allows for use of conventional ovens or furnaces. The
temperatures of solid phase sintering and HIPping for
achieving fully condensed materials are generally
significantly lower than the temperatures for liquid phase
sintering. For example, the sample P62 which uses pure Re as
the binder may be fully densified by vacuum sintering at
2200 C for one to two hours and then HIPping at about 2000 C
under a pressure of 30,000 PSI in the inert gas such as Ar for
about one hour. Notably, the use of ultra fine hard particles
with a particulate dimension less than 0.5 micron can reduce
the sintering temperature for fully densifying the hardmetals
(fine particles are several microns in size). For example, in
making the samples P62 and P63, the use of such ultra fine WC
allows for sintering temperatures. to be low, e.g., around 2000
C. This two-step process is less expensive than the ROC
method and may be used to commercial production.
[0040] The following sections describe exemplary hardmetal
compositions and their properties based on various binder
matrix materials that include at least rhenium or a nickel-
based supperalloy.
[0041] TABLE 2 provides a list of code names (lot numbers) for
some of the constituent materials used to form the exemplary
hardmetals, where Hl represents rhenium, and L1, L2, and L3
represent three exemplary commercial nickel-based
supperalloys. TABLE 3 further lists compositions of the above
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three exemplary nickel-based supperalloys, Udimet720(U720),
Rene'95(R-95), and Udimet700(U700), respectively. TABLE 4
lists compositions of exemplary hardmetals, both with and
without rhenium or a nickel-based.superalloy in the binder
matrices. For example, the material composition for Lot P17
primarily includes 88 grams of T32 (WC), 3 grams of 132 (TiC),
3 grams of A31 (TaC), 1.5 grams of H1 (Re) and 4.5 grams of L2
(R-95) as binder, and 2 grams of a wax as lubricant. Lot P58
represents a hardmetal with a nickel-based supperalloy L2 as
to the only binder material without Re. These hardmetals were
fabricated and tested to illustrate the effects of either or
both of rhenium and a nickel-based supperalloy as binder
materials on various properties of the resulting hardmetals.
TABLES 5-8 further provide summary information of compositions
and properties of different sample lots as defined above.
[0042] FIGS. 3 through 8 show measurements of selected
hardmetal samples of this application. FIGS. 3 and 4 show
measured toughness and hardness parameters of some exemplary
hardmetals for the steel cutting grades. FIGS. 5 and 6 show
measured toughness and hardness parameters of some exemplary
hardmetals for the non-ferrous cutting grades. Measurements
were performed before and after the solid-phase sintering HIP
process and the data suggests that the HIP process
significantly improves both the toughness and the hardness of
the materials. FIG. 7 shows measurements of the hardness as a
function of temperature for some samples. As a comparison,
FIGS. 7 and 8 also show measurements of commercial C2 and C6
carbides under the same testing conditions, where FIG. 7 shows
the measured hardness and FIG. 8 shows measured change in
hardness from the value at the room temperature (RT).
Clearly, the hardmetal samples based on the compositions
described here outperform the commercial. grade materials in
terms of the hardness at high temperatures. These results
demonstrate that the superior performance of binder matrices
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with either or both of Re and a nickel--based supperalloy as
binder materials in comparison with Co-based binder matrix
materials.
TABLE 2
Powder
Code Note
Composition
T32 WC Particle size 1.5 m, from Alldyne
T35 WC Particle size 15 pm, from Alldyne
Y20 Mo Particle size 1.7-2.2 pm, from Alldyne
L3 U-700 -325 Mesh, special metal Udimet 700
Ll U-720 -325 Mesh, Special Metal, Udimet 720
L2 Re-95 -325 Mesh, Special Metal, Rene 95
Hl Re -325 Mesh, Rhenium Alloy Inc.
132 TC from AEE, Ti-302
121 TiB2 from AEE, Ti-201, 1-5 pm
A31 TaC from AEE, TA-301
Y31 Mo2C from AEE, MO-301
D31 VC from AEE, VA-301
Bl Co from AEE, CO-101
K1 Ni from AEE, Ni-101
K2 Ni from AEE, Ni-102
113 TiN from Cerac, T-1153
C21 ZrB2 from Cerac, Z-1031
Y6 Mo from AEE Mo+100, 1-2 pm
L6 Al from AEE Al-100, 1-5 pm
R31 B4C from AEE Bo-301, 3 pm
T3.8 WC Particle size 0.8 pm, Alldyne
T3.4 WC Particle size 0.4 pm, OMG
T3.2 WC Particle size 0.2 m, 0MG
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TABLE 3
Ni Co Cr Al Ti Mo Nb W Zr B C V
R95 61.982 8.04 13.16 3.54 2.53 3.55 3.55 3.54 0.049 0.059
U700 54.331 17.34 15.35 4.04 3.65 5.17 .028 .008 .04 .019 .019 .005
U720 56.334 15.32 16.38 3.06 5.04 3.06 0.01 1.30 .035 .015 .012 .004
TABLE 4
Lot No Composition (units in grams)
P17 H1=1.5, L2=4.5, 132=3, A31=3', T32=88, Wax=2
P18 H1=3, L2=3, 132=3, A31=3, T32=88, Wax=2
P19 H1=1.5, L3=4.5, 132=3, A31=3, T32=88, Wax=2
P20 H1=3, L3=3, 132=3, A31=3, T32=88, Wax=2
P25 H1=3.75, L2=2.25, I32=3, A31=3, T32=88, Wax=2
P25A H1=3.75, L2=2.25, 132=3, A31=3, T32=88, Wax=2
P31 H1=3.44, B1=4.4, T32=92.16, Wax=2
P32 H1=6.75, B1=2.88, T32=90.37, Wax=2
P33 H1=9.93, 81=1.41, T32=88.66, Wax=2
P34 L2=14.47, I32=69.44, Y31=16.09
P35 H1=8.77, L2=10.27, I32=65.73, Y31=15.23
P36 H1=16.66; L2=6.50, 132=62.4, Y31=14.56
P37 H1=23.80, L2=3.09, I32=59.38, Y31=13.76
P38 K1=15.51, I32=68.60, Y31=15.89
P39 K2=15.51, I32=68.60, Y31=15.89
P40 H1=7.57, L2=2.96, I32=5.32, A31=5.23, T32=78.92, Wax=2
P40A H1=7.57, L2=2.96, I32=5.32, A31=5.2:3, T32=78.92, Wax=2
P41 H1=11.1, L2=1.45, I32=5.20, A31=5.11, T32=77.14, Wax=2
P41A H1=11.1, L2=1.45, I32=5.20, A31=5.11, T32=77.14, Wax=2
P42 H1=9.32, L2=3.64, 132=6.55, A31=6.44, 121=0.40, R31=4.25, T32=69.4
Wax=2
P43 H1=9.04, L2=3.53, I32=6.35, A31=6.24, I21=7.39, R31=0.22, T32=67.2
Wax=2
P44 H1=8.96, L2=3.50, 132=14.69, A31=6.19, T32=66.67, Wax=2
P45 H1=9.37, L2=3.66, 132=15.37, A31=6.47, Y31=6.51, T32=58.61, Wax=2
P46 H1=11.40, L2=4.45, 132=5.34, A31=5.25, T32=73.55, wax=2
P46A H1=11.40, L2=4.45, I32=5.34, A31=5.25, T32=73.55, Wax=2
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P47 H1=11.35, 81=4.88, I32=5.32, A31=5.23, T32=73.22, Wax=2
P47A H1=11.35, 81=4.88, I32=5.32, A31=5.23, T32=73.22, Wax=2
P48 H1=3.75, L2=2.25, I32=5, A31=5, T32=84, Wax=2
P49 111=7.55, B1=3.25, 132=5.31, A31=5.21, T32=78.68, Wax=2
P50 H1=4.83, L2=1.89, I32=5.31, A31=5.22, T32=82.75, Wax=2
P51 H1=7.15, L2=0.93, I32=5.23, A31=5.14, T32=81.55, Wax=2
P52 B1=8, D31=0.6, T3.8=91.4, Wax=2
P53 B1=8, D31=0.6, T3.4=91.4, Wax=2
P54 B1=8, D31=0.6, T3.2=91.4, Wax=2
P55 H1=1.8, B1=7.2, D31=0.6, T3.4=90.4, Wax=2
P56 H1=1.8, B1=7.2, D31=0.6, T3.2=90.4, Wax=2
P56A H1=1.8, B1=7.2, D31=0.6, T3.2=90.4, Wax=2
P57 H1=1.8, B1=7.2, T3.2=91, Wax=2
P58 L2=7.5, D31=0.6, T3.2=91.9, Wax=2
P59 H1=0.4, B1=3, L2=4.5, D31=0.6, T3.2=91.5, Wax=2
P62 H1=14.48, I32=5.09, A31=5.00, T3.2=75.43, Wax=2
P62A H1=14.48, 132=5.09, A31=5.00, T3.2=75.43, Wax=2
P63 H1=12.47, L2=0.86, I32=5.16, A31=5.07, T3.2=76.45, Wax=2
P65 H1=7.57, L2=2.96, 132=5.32, A31=5.23, T3.2=78.92, Wax=2
P65A H1=7.57, L2=2.96, I32=5.32, A31=5.23, T3.2=78.92, Wax=2
P66 H1=27.92, I32=4.91, A31=4.82, T3.2=62.35, Wax=2
P67 H1=24.37, L3=1.62, I32=5.04, A31=4.95, T32=32.01, T33=32.01, Wax=2
P69 L2=7.5, D31=0.4, T3.2=92.1, Wax=2
P70 L1=7.4, D31=0.3, T3.2=92.3, Wax=2
P71 L3=7.2, D31=0.3, T3.2=92.5, Wax=2
P72 H1=1.8, B1=7.2, D31=0.3, T3.2=90.7, Wax=2
P73 H1=1.8, B1=4.8, L2=2.7, D31=0.3, T3.2=90.4, Wax=2
P74 H1=1.8, B1=3, L2=4.5, D31=0.3, T3.2=90.4, Wax=2
P75 H1=0.8, B1=3, L2=4.5, D31=0.3, T3.2=91.4,. Wax=2
P76 H1=0.8, B1=3, L1=4.5, D31=0.3, T3.2=91.4, Wax=2
P77 H1=0.8, B1=3, L3=4.5, D31=0.3, T3.2=91.4, Wax=2
P78 H1=0.8, B1=4.5, L1=3, D31=0.3, T3.2=91.4, Wax=2
P79 H1=0.8, B1=4.5, L3=3.1, D31=0.3, T3.2=91.3, Wax=2
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[0043] Several exemplary categories of hardmetal compositions
are described below to illustrate the above general designs of
the various hardmetal compositions to include either of Re and
Nickel-based superalloy, or both. The exemplary categories of
hardmetal compositions are defined based on the compositions
of the binder matrices for the resulting hardmetals or
cermets. The first category uses a binder matrix having pure
Re, the second category uses a binder matrix having a Re-Co
alloy, the third category uses a binder matrix having a Ni-
i0 based superalloy, and the fourth category uses a binder matrix
having an alloy having a Ni-based superalloy in combination
with of Re with or without Co.
[0044] In general, hard and refractory particles used in
hardmetals of interest may include, but are not limited to,
Carbides, Nitrides, Carbonitrides, Borides, and Silicides.
Some examples of Carbides include WC, TiC, TaC, HfC, NbC, Mo2C,
Cr2C3, VC, ZrC, B4C, and SiC. Examples of Nitrides include
TIN, ZrN, HfN, VN, NbN, TaN, and BN. Examples of
Carbonitrides include Ti(C,N), Ta(C,N), Nb(C,N), Hf(C,N),
Zr(C,N), and V(C,N). Examples of Borides include TiB2r ZrB2,
HfB2, TaB2, VB2r MoB2, WB, and W2B. In addition, examples of
Silicides are TaSi2, Wsi2, NbSi2, and MoSi2. The above-
identified four categories of hardmetals or cermets can also
use these and other hard and refractory particles.
[0045] In the first category of hardmetals based on the pure
Re alloy binder matrix, the Re may be approximately from 5% to
40% by volume of all material compositions used in a hardmetal
or cermet. For example, the sample with a lot No. P62 in
TABLE 4 has 10% of pure Re, 70%of WC, 15% of TiC, and 5% of
TaC by volume. This composition approximately corresponds to
14.48% of Re, 75.43% of WC, 5.09% of TIC and 5.0% of TaC by
weight. In fabrication, the Specimen P62-4 was vacuum sintered
at 2100 C for about one hour and 2158 C for about one hour.
The density of this material is about 14.51g/cc, where the
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calculated density is 14.50 g/cc. The average hardness Hv is
2627 35 Kg/mm2for 10 measurements taken at the room
temperature under a load of 10 Kg. The measured surface
fracture toughness K5 is about 7.4 x106 Pa-m1/2 estimated by
Palmvist crack length at a load of 10 Kg.
[0046] Another example under this category is P66 in TABLE 4.
This sample has about 20% of Re, 60% of WC, 15% of TiC, and 5%
of TaC by volume in composition. In the weight percentage,
this sample has about 27.92% of Re, 62.35% of WC, 4.91% of
1o TiC, and 4.82% of TaC. The Specimen P66-4 was first processed
with a vacuum sintering process at about 2200 C for one hour
and was then sintered in the solid-phase with a HIP process to
remove porosities and voids. The density of the resulting
hardmetal is about 14.40g/cc compared to the calculated
density of 15.04g/cc. The average hardness Hv is about
2402 44 Kg/mm2 for 7 different measurements taken at the room
temperature under a load of 10 Kg. The surface fracture
toughness Ks, is about 8.1 x106 Pa=m112. The sample P66 and
other compositions described here with a high concentration of
Re with a weight percentage greater than 25%, as the sole
binder material or one of two or more different binder
materials in the binder, may be used for various applications
at high operating temperatures and may be manufactured by
using the two-step process based on solid-phase sintering.
[0047] The microstuctures and properties of Re bound multiples
types of hard refractory particles, such as carbides,
nitrides, carbonnitrides, silicides, and bobides, may provide
advantages over Re-bound WC material. For example, Re bound
WC-TiC-TaC may have better crater resistance in steel cutting
than Re bound WC material. Another example is materials
formed by refractory particles of M02C and TIC bound in a Re
binder.
[0048] For the second category with a Re-Co alloy as the
binder matrix, the Re-Co alloy may be about from 5 to 40 Vol%
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of all material compositions used in the composition. In some
implementations, the Re-to-Co ratio in the binder may vary
from 0.01 to 0.99 approximately. Inclusion of Re can improve
the mechanical properties of the resulting hardmetals, such as
hardness, strength and toughness special at high temperature
compared to Co bounded hardmetal. The higher Re content is
the better high temperature properties are for most materials
using such a binder matrix.
[0049] The sample P31 in TABLE 4, is one example within this
1o category with 2.5% of Re, 7.5% of Co, and 90% of WC by volume,
and 3.44% of Re, 4.40% of Co and 92.12% of WC by weight. In
fabrication, the Specimen P31-1 was vacuum sintered at 1725C
for about one hour. slight under sintering with some
porosities and voids. The density of the resulting hardmetal
is about 15.16 g,/cc (calculated density at 15.27 g/cc). The
average hardness Hv is about 1889 18 Kg/mm 2 at the room
temperature under 10 Kg and the surface facture toughness Ksc
is about 7.7 x106 Pa.m112. In addition, the Specimen P31-1 was
treated with a hot isostatic press (HIP) process at about
1600C / 15Ksi for about one hour after sintering. The HIP
reduces or substantially eliminates the porosities and voids
in the compound to increase the material density. After HIP,
the measured density is about 15.25g/cc (calculated density at
15.27 g/cc). The measured hardness Hv is about 1887 12 Kg/mm2
at the room temperature under 10 Kg. The surface fracture
toughness KSc is aobut 7. 6 x106 Pa = ml/2.
[0050] Another example in this category is P32 in TABLE 4 with
5.0% of Re, 5.0% of Co, and 90% of WC in volume (6.75% of Re,
2.88% of Co and 90.38% of. WC in weight). The Specimen P32-4
was vacuum sintered at 1800C for about one hour. The measured
density is about 15.58 g/cc in comparison with the calculated
density at 15.57 g/cc. The measured hardness Hv is about 2065
Kg/mm2 at the room temperature under 10 Kg. The surface
fracture toughness KSc is about 5.9 x106 Pa=m1/2. The Specimen
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P32-4 was also HIP at 1600C / 15Ksi for about one hour after
Sintering.. The measured density is about 15.57g/cc
(calculated density at 15.57g/cc). The average hardness.Hv
is about 2010 12 Kg/mm2 at the room temperature under 10 Kg.
The surface fracture toughness Ksc is about 5.8 x106 Pa Ml/2.
[0051] The third example is P33 in TABLE 4 which has 7.5% of
Re, 2.5% of Co, and 90% of WC by volume and 9.93% of Re, 1.41%
of Co and 88.66% of WC by weight. In fabrication, the
Specimen P33-7 was vacuum sintered at 1950C for about one hour
and was under sintering with porosities and voids. The
measured density is about 15.38 g/cc (calculated density at
15.87 g/cc). The measured hardness Hv is about 2081 Kg/mm2 at
the room temperature under a force of 10 Kg. The surface
fracture toughness Ksc is about 5.6 x106 Pa=m1/2. The Specimen
P33-7 was HIP at 1600C / 15Ksi for about one hour after
Sintering. The measured density is about 15.82g/cc
(calculated density-15.87 g/cc). The average hardness Hv is
measured at about 2039 18 Kg/mm2 at the room temperature under
10 Kg. The surface fracture toughness Ksc is about 6.5 x106
.
Pa-ml/2
TABLE 5 Re-Co alloy bound hardmetals
Temperature Density
Hv Ksc
C g/cc Grain
Sinter HIP Calculated Measured Kg/jZ2 x10 size
Pal - m2/2
P55-1 1350 1300 14.77 14.79 2047 8.6 Ultra-
fine
P56-5 1360 1300 14.77 14.72 2133 8.6 Ultra-
fine
P56A- 1350 1300 14.77 14.71 2108 8.5 Ultra-
4 fine
P57-1 1350 1300 14.91 14.93 1747 12.3 Fine
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[0052] The samples P55, P56, P56A, and P57 in TABLE 4 are also
examples for the category with a Re-Co alloy as the binder
matrix. These samples have about 1.8% of Re, 7.2% of Co, 0.6%
of VC except that P57 has no VC, and finally WC in balance.
These different compositions are made to study the effects of
hardmetal grain size on Hv and Ksc. TABLE 5 lists the
results.
TABLE 6 Properties of Ni-based superalloys, Ni, Re, and Co
Test
Temp. R-95 U-700 U720 Nickel Rhenium Cobalt
C
Density
21 8.2 7.9 8.1 8.9 21 8.9
(g/c.c.)
Melting
1255 1205 1210 1450 3180 1495
Point ( C)
Elastic
Modulus 21 30.3 32.4. 32.2 207 460 211
(Gpa)
21 1620 1410 1570 317 1069 234
Ultimate
760 1170 1035 1455
Tensile
800 620
Strength
870 690 1150
(Mpa)
1200 414
21 1310 965 1195 60
0.2%
760 1100 825 1050
Yield
800
Strength
870 635
(Mpa)
1200
21 15 17 13 30 >15
Tensile 760 15 20 9
Elongation 800 5
(%) 870 27
1200 2
Oxidation
Excellent Excellent Excellent Good Poor Good
Resistance
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[0053] The third category is based on binder matrices with Ni-
based superalloys from 5 to 40% in volume of all materials in
the resulting hardmetal. Ni-based superalloys are a family of
high temperature alloys with y' strengthening. Three different
strength alloys, Rene'95, Udimet 720, and Udimet 700 are used
as examples to demonstrate binder strength effects on
mechanical properties of hardmetals. The Ni-based superalloys
have a high strength specially at elevated temperatures.
Also, these alloys have good environmental resistance such as
1o resistance to corrosion and oxidation at elevated temperature.
Therefore, Ni-based superalloys can be used to increase the
hardness of Ni-based superalloy bound hardmetals when compared
to Cobalt bound hardmetals. Notably, the tensile strengths of
the Ni-based supperalloys are much stronger than the common
binder material cobalt as shown by TABLE 6. This further
shows that Ni-based supperalloys are good binder materials for
hardmetals.
[0054] One example for this category is P58 in TABLE 4 which
has 7.5% of Rene'95, 0.6% of VC, and 91.9% of WC in weight and
compares to cobalt bound P54 in TABLE 4 (8% of Co, 0.6% of VC,
and 91.4% of WC). The hardness of P58 is significant higher
than P54 as shown in TABLE 7.
TABLE 7 Comparison of P54 and P58
Ksc
Sintering HIP Hv, Kg/mm2
x106 Pa m112
P54-1 1350C / 1hr 2094 8.8
P54-2 1380C / 1hr 2071 7.8
P54-3 1420C / 1hr 1305 C 2107 8.5
P58-1 1350, 1380, 1400, 1420, 15KSI under Ar
1450, 1475 for 1 hour at 1 hour 2322 7.0
each temperature
P58-3 1450C / 1hr 2272 7.4
P58-5 1500C / 1hr 2259 7.2
P58-7 1550C / lhr 2246 7.3
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[0055] The fourth category is Ni-based superalloy plus Re as
binder, e.g., approximately from 5% to 40 % by volume of all
materials in the resulting hardmetal or cermet. Because
addition of Re increases the melting point of binder alloy of
Ni-based superalloy plus Re, the processing temperature of
hardmetal with Ni-based superalloy plus Re binder increases as
the Re content increases. Several hardmetals with different
Re concentrations are listed in TABLE 8. TABLE 9 further
shows the measured properties of the hardmetals in TABLE 8.
TABLE 8 Hardmetal with Ni-based superalloy plus Re binder
Composition, weight % Re to Sintering
U- U- Binder Temperature
Re Rene95 WC Tic TaC
700 720 Ratio C
P17 1.5 0.25 88 3 3 25% 1600-1750
P18 3 05 88 3 3 50% 1600-1775
P25 3.75 0.625 88 3 3 62.5% 1650-1825
P48 3.75 0.625 84 5 5 62.5% 1650-1825
P50 4.83 1.89 82.75 5.31 5.22 71.9% 1675-1850
P40 7.57 2.96 78.92 5.32 5.23 71.9% 1675-1850
P46 11.40 4.45 73.55 5.34 5.24 71.9% 1675-1850
P51 7.15 0.93 81.55 5.23 5.14 88.5% 1700-1900
P41 11.10 1.45 77.14 5.20 5.11 88.5% 1700-1900
P63 12.47 0.86 76.45 5.16 5.07 93.6% 1850-2100
P19 1.5 4.5 88 3 3 25% 1600-1750
P20 3 3 88 3 3 50% 1600-1775
P67 24.37 1.62 64.02 5.04 4.95 93.6% 1950-2300
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TABLE 9 Properties of hardmetals bound by Ni-based
superalloy and Re
Temperature, C Density, g/cc Hv Ksc
Sinter HIP Calculated Measured Kg/mm2 xiO6Pa=m1"2
P17 1700 14.15 14.18 2120 6.8
P17 1700 1600 14.15 14.21 2092 7.2
P18 1700 14.38 14.47 2168 5.9
P18 1700 1600 14.38 14.42 2142 6.1
P25 1750 14.49 14.41 2271 6.1
P25 1750 1600 14.49 14.48 2193 6.5
P48 1800 1600 13.91 13.99 2208 6.3
P50 1800 1600 13.9 13.78 2321 6.5
P40 1800 13.86 13.82 2343
P40 1800 1600 13.86 13.86 2321 6.3
P46 1800 13.81 13.88 2282 7.1
P46 1800 1725 13.81 13.82 2326 6.7
P51 1800 1600 14.11 13.97 2309 6.6
P41 1800 1600 14.18 14.63 2321 6.5
P63 2000 14.31 14.37 2557 7.9
P19 1700 14.11 14.11 2059 7.6
P19 1700 1600 14.11 2012 8.0
P20 1725 14.35 14.52 2221 6.4
P20 1725 1600 14.35 14.35 2151 7.0
P67 2200 14.65 14.21 2113 8.1
P67 2200 1725 14.65 14.34 2210 7.1
(0056] Another example under the fourth category uses a Ni-
based superalloy plus Re and Co as binder which is also about
5% to 40% by volume. Exemplary compositions of hardmetals
1o bound by Ni-based superalloy plus Re and Co are list in TABLE
10.
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TABLE 10 Composition of hardmetals bound by Ni-based
superalloy plus Re and Co
Composition, weight %
Re Co Rene95 U-720 U-700 WC VC
P73 1.8 4.8 2.7 90.4 0.3
P74 1.8 3 4.5 90.4 0.3
P75 0.8 3 4.5 91.4 0.3
P76 0.8 3 4.5 91.4 0.3
P77 0.8 3 4.5 91.4 0.3
P78 0.8 4.5 3 91.4 0.3
P79 0.8 4.5 3.1 91.3 0.3
[0057] Measurements on selected samples have been performed to
s.tudy properties of the binder matrices with Ni-based
superalloys. In general, Ni-based supperallosy not only
exhibit excellent strengths at elevated temperatures but also
possess outstanding resistances to oxidation and corrosion at
1o high temperatures. Ni-based superalloys have complex.
microstructures and strengthening mechanisms. In general, the
strengthening of Ni-based superalloys is primarily due to
precipitation strengthening of y-y' and solid-solution
strengthening. The measurements the selected samples
demonstrate that Ni-based supperalloys can be used as a high-
performance binder materials for hardmetals.
[0058] TABLE 11 lists compositions of selected samples by
their weight percentages of the total weight of the
hardmetals. The WC particles in the samples are 0.2 }.Im in
size. TABLE 12 lists the conditions for the two-step process
performed and measured densities, hardness parameters, and
toughness parameters of the samples. The,Palmgvist fracture
toughness Ksc is calculated from the total crack length of
Palmgvist crack which is produced by the Vicker Indentor:
Ksc=0.087*(Hv*W)1"2. See, e.g., Warren and H. Matzke,
Proceedings Of the International Conference On the Science of
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ATTORNEY DOCKET 6 14791-002W01 =
Hard Materials, Jackson, Wyoming, Aug 23-28, 1981. Hardness
Hv and Crack Length are measured at a load of 10 Kg for 15
seconds. During each measurement, eight indentations were
made on each specimen and the average value was used in
computation of the listed data.
TABLE 11
Weight % Vol %
Re in '
Re Co R-95 WC VC Binder
Binder
P54 0 8 0 91.4 0.6 0 13.13
P58 0 0 7.5 91.9 0.6 0 13.25
P56 1.8 7.2 0 90.4 0.6 20 13.20
P72 1.8 7.2 0 90.7 0.3 20 13.18
P73 1.8 4.8 2.7 90.4 0.3 20 14.00
P74 1.8 3 4.5 90.4 0.3 20 14.24
TABLE 12
Palmgvist
Cal. Heasu.
Sample Sinter HIP Hardness,Hv Toughness
Density Density
Code Condition Condition Kg/mm2 Ksc,
g/c.c. g/c.c.
x106Pa = m112
1360 C/lhr 14.58 2062 35 8.9 0.2
P54-5 14.63
1360 C/lhr 1305 C/15KSI/lhr 14.55 2090 22 8.5 0.2
1550 C/lhr 14.40 2064 12 7.9 0.2
P58-7 14.50
1550 C/lhr 1305 C/15KS1/lhr 14.49 2246 23 7.3 0.1
1360 C/lhr 14.71 2064 23 8.2 0.1
P56-5 14.77
1360 C/lhr 1305 C/15KSI/lhr 1.4.72 2133 34 8.6 0.2
1475 C/lhr 14.77 2036 34 8.5 0.6
P72-6 14.83
1475 C/lhr 1305 C/15KS1/lhr 14.91 2041 30 9.1 0.4
1475 C/lhr 14.70 2195 23 7.7 0.1
P73-6 14.73
1475 C/lhr 1305 C/15KS1/lhr 14.72 2217 25 8.1 0.2
1500 C/lhr
and 14.69 2173 30 7.4 0.3
1520 C/lhr
P74-5 14.69
1500 C/lhr
and 1305 C/15KSI/lhr 14.74 .2223 34 7.7 0.1
1520 C/ lhr
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[0059] Among the''tested samples, the sample P54 uses the
conventional binder consisting of Co. The Ni-supperalloy R-95
is used in the sample P58 to replace Co as the binder in the
sample P54. As a result, the Hv increases from 2090 of P54 to
2246 of P58. In the sample P56, the mixture of Re and Co is
used to replace Co as binder and the corresponding Hv
increases from 2090 of P54 to 2133 of P56. The samples P72,
P73, P74 have the same Re content but different amounts of Co
and R95. The mixtures of Re, Co, and R95 are used in samples
P73 and P74 to replace the binder having a mixture of Re and
Co as the binder in the sample 72. The hardness Hv increases
from 2041(P72) to 2217 (P73) and 2223(P74).
TABLE 13
Weight % Vol. %
WC WC Re in
Re R-95 Co Tic TaC Binder
(2 m) (0.2 m) Binder
P17 1.5 4.5 0 3 3 88 0 25 8.78
P18 3 3 0 3 3 88 0 50 7.31
P25 3.75 2.25 0 3 3 88 0 62.5 6.57
P48 3.75 2.25 0 5 5 84 0 62.5 6.3
P50 4.83 1.89 0 5.31 5.22 82.75 0 71.9 6.4
P51 7.15 0.93 0 5.23 5.14 81.55 0 88.5 6.4
P49 7.55 0 3.25 5.31 5.21 78.68 0 69.9 10
P40A 7.57 2.96 0 5.32 5.23 78.92 0 71.9 10
P63 12.47 0.86 0 5.16 5.07 0 76.45 93.6 10
P62A 14.48 0 0 5.09 5.00 0 75.43 100 10
P66 27.92 0 0 4.91 4.82 0 62.35 100 20
[0060] Measurements on selected samples have also been
performed to further study properties of the binder matrices
with Re in the binder matrices. TABLE 13-lists the tested
samples. The WC particles with two different particle sizes
of 2 m and 0.2 m were used. TABLE 14 lists the conditions
for the two-step process performed and the measured densities,
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hardness parameters, and toughness parameters of the selected
samples.
TABLE 14
Cal. Measu. Palmqvist
Sample Sinter HIP Hardness,Hv
Density Density Toughness**
Code Condition Condition Kg/mm2
g/c.c. g/c.c._ Ksc, MPamo.s
P17-5 1800 C/lhr 1600 C/15KSI/lhr 14.15 14.21 2092 3 7.2 0.1
P18-3 1800 C/lhr 1600 C/15KSI/lhr 14.38 14.59 2028 88 6.8 0.3
P25-3 1750 C/lhr 1600 C/15KSI/lhr 14.49 14.48 2193 8 6.5 0.1
P48-1 1800 C/lhr 1600 C/15KSI/lhr 13.91 13.99 2208 12 6.3 0.4
P50-4 1800 C/lhr 1600 C/15KSI/lhr 13.9 13.8 2294 20 6.3 0.1
P51-1 1800 C/lhr 1600 C/15KSI/lhr 14.11 13.97 2309 6 6.6 0.1
P40A-1 1800 C/lhr 1600 C/15KSI/lhr 13.86 13.86 2321 10 6.3 0.1
P49-1 1800 C/lhr 1600 C/15KSI/lhr 13.91 13.92 2186 29 6.5 0.2
P62A-6 2200 C/lhr 1725 C/30KSI/lhr 14.5 14.41 2688 22 6.7 0.1
P63-5 2200 C/lhr 17250C/30KSI/lhr 14.31 14.37 2562 31 6.7 0.2
P66-4 2200 C/lhr 15.04 14.40 2402 44 8.2 0.4
P66-4 2200 C/lhr 1725 C/30KSI/lhr 15.04 14.52
1725 C/30KSI/lhr
P66-4 2200 C/lhr 15.04 14.53 2438 47 6.9 0.2
+1950 C/30KSI/lhr
P66-5 2200 C/lhr 15.04 14.33 2092 23 7.3 0.3
P66-5 2200 C/lhr 17250C/30KSI/lhr 15.04 14.63
1725 C/30KSI/lhr
P66-5 2200 C/lhr 15.04 14.66 2207 17 7.1 0.2
+1850 C/30KSI/lhr
[00611 TABLE 15 further shows measured hardness parameters
under various temperatures for the selected samples, where the
Knoop hardness Hk were measured under a load of 1 Kg for 15
seconds on a Nikon QM hot hardness tester and R is a ratio of
Hk at an elevated testing temperature over Hk at 25 C. The hot
hardness specimens of C2 and C6 carbides were prepared from
inserts SNU434 which were purchased from MSC Co.(Melville,
NY).
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TABLE 15
(each measured value at a given temperature is an averaged
value of 3 different measurements)
Testing Temperature, C
Lot No. Hv @25
25 400 500 600 700 800 900
1880 1720 1653 1553 1527 2092
Hk, Kg/mm 2 10 17 25 29 6 3
P17-5
R, % 100 91 88 83 81
1773 1513 1467 1440 1340 2028
Hk, Kg/mm2 32 12 21 10 16 88
P18-3
R, % 100 85 83 81 76
Hk, Kg/mm 2 1968 1813 1710 1593 2193
45 12 0 5 8
P25-3
R, % 100 92 87 81
Hk, Kg/mm2 2000 1700 1663 1583 1540 2321
35 17 12 21 35 10.
P40A-1
R, % 100 85 83 79 77
Hk, Kg/mm2 1925 1613 1533 1477 1377 2208
25 15 29 6 15 12
P48-1
R, % 100 84 80 77 72
2023 1750 1633 1600 2186
Hk, Kg/mm2
P49-1 32 0 6 17 29
R, % 100 87 81 79
Hk, Kg/mm2 2057 1857 1780 1713 1627 2294
P50-4 25 15 20 6 40 20
R, % 100 90 87 83 79
Hk, Kg/mm2 2050 1797 1743 1693 1607 2309
P51-1 26 6 35 15 15 6
R, % 100 88 85 83 78
Hk, Kg/mm 2 2228 2063 1960 1750 2688
P62A-6 29 25 76 0 22
R, % 100 93 88 79
Hk, Kg/mm2 1887 1707 1667 1633 1603 2562
P63-5 6 35 15 6 25 31
R, % 100
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Hk, Kg/mm2 1503 988 711 584 1685
C2 Carbide 38 9 0 27 16
R, % 100 66 47 39
1423 1127 1090 1033 928 1576
Hk, Kg/mm 2
C6 Carbide 23 25 10 23 18 11
R, % 100 79 77 73 65
[0062] The inclusion of Re in the binder matrices of the
hardmetals increases the melting point of binder alloys that
include Co-Re, Ni superalloy-Re, Ni superalloy-Re-Co. For
example, the melting point of the sample P63 is much higher
than the temperature of 2200 C used for the solid-phase
sintering process. Hot hardness values of such hardmetals
with Re in the binders (e.g., P17 to 263) are much higher than
conventional Co bound hardmetals( C2 and C6 carbides). In
particular, the above measurements reveal that an increase in
the concentration of Re in the binder increases the hardness
at high temperatures. Among the tested samples, the sample
P62A with pure Re as the binder has the highest hardness. The
sample P63 with a binder composition of 94% of Re and 6 % of
the Ni-based supperalloy R95 has the second highest hardness.
.The samples P40A(71.9%Re-29.l%R95), P49(69.9%Re-30.1%R95),
251(88.5%Re-11.5%R95), and P50(71.9%Re-28.1%R95) are the next
group in their hardness. The sample P48 with 62.5% of Re and
37.5% of R95 in its binder has the lowest hardness at high
temperatures among the tested materials in part because its Re
content is the lowest.
[0063] In yet another category, a hardmetal or cermet may
include TIC and TiN bonded in a binder matrix having Ni and Mo
or Mo2C. The binder Ni of cermet can be fully or partially
replaced by Re, by Re plus Co, by Ni-based superalloy, by Re
plus Ni-based superalloy, and by Re plus Co and Ni-based
superalloy. For example, P38 and 239 are a typical Ni bound
cermet. The sample P34 is Rene95 bound Cermet. The P35, P36,
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P37, and P45 are Re plus Rene95 bound cermet. Compositions of
P34, 35, 36, 37, 38, 39, and 45 are list in TABLE 16.
TABLE 16 Composition of P34 to P39
Weight %
Re Rene95 Ni 1 Ni 2 TiC Mo2C WC TaC
P34 14.47 69.44 16.09
P35 8.77 10.27 65.37 15.23
P36 16.6 6.50 62.40 14.46
P37 23.8 3.09 59.38 13.76
P38 15.51 68.60 15.89
P39 15.51 68.60 15.89
P45 9.37 3.66 15.37 6.51 58.6 6.47
[0064] The above compositions for hardmetals or cermets may be
used for a variety of applications. For example, such a
material may be used to form a wear part in a tool that cuts,
grinds, or drills a target object by using the wear part to
remove the material of the target object. Such a tool may
include a support part made of a different material, such as a
steel. The wear part is then engaged to the support part as
an insert. The tool may be designed to include multiple
inserts engaged to the support part. For example, some mining
drills may include multiple button bits made of a hardmetal
material. Examples of such a tool includes a drill, a cutter
such as a knife, a saw, a grinder, a drill. Alternatively,
hardmetals descried here may be used to form the entire head
of a tool as the wear part for cutting, drilling or other
machining operations. The hardmetal particles may'also be
used to form abrasive grits for polishing or grinding various
materials. In addition, such hardmetals may also be used to
construct housing and exterior surfaces or layers for various
devices to meet specific needs of the operations of the
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devices or the environmental conditions under which the
devices operate.
[0065] More specifically, the hardmetals described here may be
used to manufacture cutting tools for machining of metal,
composite, plastic and wood. The cutting tools may include
indexable inserts for turning, milling, boring and drilling,
drills, end mills, reamers, taps, hobs and milling cutters.
Since the temperature of the cutting edge of such tools may be
higher than 500 C during machining, the hardmetal
compositions for high-temperature operating conditions
described above may have special advantages when used in such
cutting tools, e.g., extended tool life and improved
productivity by such tools by increasing the cutting speed.
[0066] The hardmetals described here may be used to
manufacture tools for wire drawing, extrusion, forging and
cold heading. Also as mold and Punch for powder process. In
addition, such hardmetals may be used as wear-resistant
material for rock drilling and mining.
[0067] Only a few implementations and examples are disclosed.
However, it is understood that variations and enhancements may
be made without departing from the spirit of and are intended
to be encompassed by the following claims.
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